// This file is part of Eigen, a lightweight C++ template library
// for linear algebra.
//
// Copyright (C) 2012 Désiré Nuentsa-Wakam <desire.nuentsa_wakam@inria.fr>
//
// This Source Code Form is subject to the terms of the Mozilla
// Public License v. 2.0. If a copy of the MPL was not distributed
// with this file, You can obtain one at http://mozilla.org/MPL/2.0/.

#ifndef EIGEN_SPARSELU_UTILS_H
#define EIGEN_SPARSELU_UTILS_H

namespace Eigen {
namespace internal {

/**
 * \brief Count Nonzero elements in the factors
 */
template<typename Scalar, typename StorageIndex>
void
SparseLUImpl<Scalar, StorageIndex>::countnz(const Index n, Index& nnzL, Index& nnzU, GlobalLU_t& glu)
{
	nnzL = 0;
	nnzU = (glu.xusub)(n);
	Index nsuper = (glu.supno)(n);
	Index jlen;
	Index i, j, fsupc;
	if (n <= 0)
		return;
	// For each supernode
	for (i = 0; i <= nsuper; i++) {
		fsupc = glu.xsup(i);
		jlen = glu.xlsub(fsupc + 1) - glu.xlsub(fsupc);

		for (j = fsupc; j < glu.xsup(i + 1); j++) {
			nnzL += jlen;
			nnzU += j - fsupc + 1;
			jlen--;
		}
	}
}

/**
 * \brief Fix up the data storage lsub for L-subscripts.
 *
 * It removes the subscripts sets for structural pruning,
 * and applies permutation to the remaining subscripts
 *
 */
template<typename Scalar, typename StorageIndex>
void
SparseLUImpl<Scalar, StorageIndex>::fixupL(const Index n, const IndexVector& perm_r, GlobalLU_t& glu)
{
	Index fsupc, i, j, k, jstart;

	StorageIndex nextl = 0;
	Index nsuper = (glu.supno)(n);

	// For each supernode
	for (i = 0; i <= nsuper; i++) {
		fsupc = glu.xsup(i);
		jstart = glu.xlsub(fsupc);
		glu.xlsub(fsupc) = nextl;
		for (j = jstart; j < glu.xlsub(fsupc + 1); j++) {
			glu.lsub(nextl) = perm_r(glu.lsub(j)); // Now indexed into P*A
			nextl++;
		}
		for (k = fsupc + 1; k < glu.xsup(i + 1); k++)
			glu.xlsub(k) = nextl; // other columns in supernode i
	}

	glu.xlsub(n) = nextl;
}

} // end namespace internal

} // end namespace Eigen
#endif // EIGEN_SPARSELU_UTILS_H
